JP7066129B2 - A composition for extrusion molding and a method for producing an extruded body. - Google Patents

Description

The present invention relates to a composition for extrusion molding and a method for producing an extrusion molded product using the same.

It is known to use extrusion molding for the production of ceramic products. Extrusion molding of ceramic products is a method of applying pressure to a plastic raw material called clay (sometimes referred to as kneaded soil, paste, compound, etc.) and passing it through a mouthpiece to obtain a product having a constant cross-sectional shape. Extrusion molding can be applied to products with various cross-sectional shapes by changing the shape of the base, is suitable for molding long objects with a constant cross-sectional shape, and is excellent in mass productivity. Utilizing this feature, it is used for molding automobile exhaust gas removal filters, insulators, graphite electrodes, tiles, etc., and in recent years, it has also been applied to translucent alumina tubes, insulating substrates, electrical and magnetic ceramics, and functional fibers. ing.

In the extrusion molding method, water, a binder, or the like is added to an inorganic material made of dry raw material powder to form a clay, which is then molded using a mouthpiece while applying pressure. Therefore, it is required that the composition for extrusion molding, which is a clay-like plastic raw material, has fluidity when passing through the base, that is, the molding pressure is not too high. On the other hand, the composition for extrusion molding is required to have shape retention after passing through the base. Therefore, it is desirable that the composition for extrusion molding has both of these contradictory performances.

For example, honeycombs used in exhaust gas removal filters for automobiles have improved catalytic performance by increasing the specific surface area. It is necessary to reduce the thickness of the honeycomb in order to increase the specific surface area, but if the thickness is too thin, the strength will decrease. In particular, if the strength of the molded product before firing is reduced, it is difficult to handle, and damage during manufacturing and a decrease in yield occur. The strength of the molded product is improved by increasing the amount of the binder for extrusion molding, but the viscosity of the composition for extrusion molding increases and the molding pressure during extrusion increases, so that extrusion molding tends to be difficult. On the other hand, by adding water to the composition for extrusion molding, the viscosity can be lowered and the molding pressure can be reduced, but the drying shrinkage after extrusion molding is large and the molded product is liable to crack, so that the yield is deteriorated. Therefore, an additive that simultaneously satisfies (i) the strength of the molded product is imparted with a small amount of addition (shape retention) and (ii) the degree of increase in the molding pressure due to the addition is small (fluidity). (Molding aid) is required.

The following Patent Document 1 describes that a cellulose derivative is used as a molding aid, but the cellulose derivative used is alkyl cellulose, crystalline cellulose, or the like, and it is not described that fine fibrous cellulose is used.

The following Patent Document 2 describes the raw strength (that is, reinforcing property) using carboxymethyl cellulose and / or cellulose as a binder for extrusion molding. However, the plasticity is imparted by sorbitan ester, there is no description about the fluidity due to the addition of cellulose, and there is no description that fine fibrous cellulose is used.

The following Patent Document 3 describes that modified celluloses are used as a binder and polyalkylene glycol or the like is used as a plasticizer. As the modified celluloses, methyl cellulose, ethyl cellulose, propyl cellulose and carboxy-modified cellulose are described, but the point of using fine fibrous cellulose is not described.

Japanese Unexamined Patent Publication No. 2005-306710 Japanese Unexamined Patent Publication No. 2005-073751 Special Table No. 7-505359 Gazette

It is an object of the present invention to provide an extrusion-molding composition capable of achieving both fluidity when passing through a base and shape retention after passing through a base.

The composition for extrusion molding according to the embodiment of the present invention contains an inorganic material (A), fine fibrous cellulose (B), water (C), and a binder component (D), and is in the form of fine fibers. Cellulose (B) satisfies the following conditions (a), (b), (c) and (d).
(A) Number average fiber diameter is 3 nm or more and 100 nm or less (b) Average aspect ratio is 10 or more and 1000 or less (c) Cellulose type I crystal structure (d) Extrusion according to the embodiment of the present invention having an anionic functional group The method for producing a molded body is to extrude the composition for extrusion molding to produce an extruded body.

The extrusion-molding composition according to the embodiment of the present invention has a fluidity because it suppresses an increase in molding pressure when passing through a base during extrusion molding and has shape retention after passing through the base. It is possible to achieve both the contradictory performance of shape retention.

Hereinafter, preferred embodiments of the present invention will be described in detail.

The composition for extrusion molding according to the present embodiment contains an inorganic material (A), fine fibrous cellulose (B), water (C), and a binder component (D).

As described above, the present embodiment relates to an inorganic substance-containing composition used for extrusion molding, and more specifically, a ceramic clay composition for extrusion molding prepared in a manufacturing process of a ceramic product manufactured by extrusion molding. In the above, fine fibrous cellulose (B) is used as the molding aid. The present inventors have been diligently studying to obtain a molding aid having a low molding pressure when the extrusion molding composition passes through the base and having higher strength than the conventional additive after passing through the base. Stacked. In the process of the research, we focused on fine fibrous cellulose and found that it is possible to achieve both fluidity and shape retention by adding fine fibrous cellulose. This embodiment is based on such findings.

[Inorganic material (A)]
The inorganic material (A) is the main component of the extrusion molding composition. As the inorganic material (A), various inorganic powders constituting the ceramic product can be used, and more specifically, various ceramic material powders capable of sintering or reaction sintering at a high temperature can be used, and are particularly limited. Not done. Specific examples of the inorganic material (A) include alumina, zirconia, mullite, titanium oxide, cordierite, forsterite, steatite, magnesia, calcia, silica, ferrite, oxides such as aluminum titanate, silicon carbide, and carbides. Carbides such as boron, titanium carbide and tungsten carbide (WC), nitrides such as silicon nitride, aluminum nitride, titanium nitride and boron nitride, borodies such as titanium borohydride, carbonitrides such as titanium carbonitride, glass powder, Examples thereof include plastic natural raw materials such as glass beads and clay. These may be used alone or in combination of two or more.

[Fine fibrous cellulose (B)]
The fine fibrous cellulose (B) has (a) a number average fiber diameter of 3 nm or more and 100 nm or less, (b) an average aspect ratio of 10 or more and 1000 or less, and (c) a cellulose I-type crystal structure. , And (d) those having an anionic functional group are used.

As described in (a) above, the number average fiber diameter of the fine fibrous cellulose is 3 to 100 nm, and therefore the fine fibrous cellulose is also referred to as cellulose nanofiber. The number average fiber diameter of the fine fibrous cellulose is more preferably 3 to 50 nm, still more preferably 3 to 30 nm.

Here, the number average fiber diameter of the fine fibrous cellulose can be measured as follows. That is, an aqueous dispersion of fine fibrous cellulose having a solid content of 0.05 to 0.1% by mass is prepared, and the aqueous dispersion is cast on a hydrophilized carbon film-coated grid to permeate. It is used as an observation sample of a type electron microscope (TEM). When a fiber having a large fiber diameter is included, a scanning electron microscope (SEM) image of the surface cast on the glass may be observed. Further, the observation sample may be negatively stained with, for example, 2% uranyl nitrate. Then, observation is performed using an electron microscope image at a magnification of 5000 times, 10000 times, or 50,000 times depending on the size of the constituent fibers. At that time, an axis having an arbitrary vertical and horizontal image width is assumed in the obtained image, and the sample and observation conditions (magnification, etc.) are adjusted so that 20 or more fibers intersect the axis. Then, after obtaining an observation image satisfying this condition, two random axes are drawn vertically and horizontally for each image, and the fiber diameters of the fibers intersecting the axes are visually read. In this way, images of at least three non-overlapping surface portions are taken with an electron microscope and the value of the fiber diameter of the fibers intersecting each of the two axes is read (hence, at least 20 fibers × 2 × 3 = 120). Information on the fiber diameter of the book can be obtained). The arithmetic mean of the fiber diameters thus obtained is defined as the number average fiber diameter.

As described in (b) above, the average aspect ratio of the fine fibrous cellulose is 10 to 1000, and by using the one having such an average aspect ratio together with the number average fiber diameter, the effect of achieving both fluidity and water retention can be achieved. It is thought that it can be increased. The average aspect ratio of the fine fibrous cellulose may be, for example, 50 or more, 100 or more, 800 or less, or 500 or less.

Here, the average aspect ratio of the fine fibrous cellulose can be measured as follows. That is, the number average fiber diameter is calculated according to the method described above, the number average fiber length of the fine fibrous cellulose is calculated from the same observation image, and the average aspect ratio is calculated according to the following formula using these values. ..
Average aspect ratio = number average fiber length (nm) / number average fiber diameter (nm)

As the fine fibrous cellulose as described in (c) above, those having a cellulose I-type crystal structure are used from the viewpoint of water insolubility. Cellulose type I crystals are the crystalline form of natural cellulose. Therefore, the fine fibrous cellulose (B) is a water-insoluble fiber having a crystal structure derived from natural cellulose, and is different from the water-soluble cellulose derivative added as a conventional binder component.

The fact that the fine fibrous cellulose has a cellulose I-type crystal structure means that, for example, in the diffraction profile obtained by wide-angle X-ray diffraction image measurement, 2θ = 14 ° to 17 ° and 2θ = 22 ° to 23 °. It can be identified by having a typical peak at one position.

As the fine fibrous cellulose as described in (d) above, those having an anionic functional group are used. Examples of the anionic functional group include at least one selected from the group consisting of a carboxyl group, a phosphoric acid group, a sulfonic acid group, a nitrate group, a boric acid group, and a sulfate group. As used herein, a carboxyl group is a concept that includes not only an acid type (-COOH) but also a salt type, that is, a carboxylic acid base (-COOX, where X is a cation forming a salt with a carboxylic acid). Similarly, the phosphate group, the sulfonic acid group, the nitric acid group, the boric acid group and the sulfate group are concepts that include not only the acid type but also the salt type.

In one embodiment, the carboxyl group is preferred as the anionic modifying group. Examples of the fine fibrous cellulose containing a carboxyl group include fine fibrous oxidized cellulose obtained by oxidizing the hydroxyl group of the glucose unit in the cellulose molecule and fine fiber obtained by carboxymethylating the hydroxyl group of the glucose unit in the cellulose molecule. Examples thereof include carboxymethylated cellulose.

Examples of the fine fibrous oxidized cellulose according to the preferred embodiment include those in which the hydroxyl group at the C6 position of the glucose unit in the cellulose molecule is selectively oxidized and modified to a carboxyl group. Fine fibrous oxidized cellulose is obtained by oxidizing natural cellulose such as wood pulp with an oxidizer in the presence of an N-oxyl compound and subjecting it to defibration (miniaturization). As the N-oxyl compound, a compound having a nitroxy radical generally used as an oxidation catalyst is used, for example, a piperidine nitroxy oxy radical, and particularly 2,2,6,6-tetramethylpiperidinooxy radical (TEMPO). ) Or 4-acetamide-TEMPO is preferred. The TEMPO-oxidized fine fibrous cellulose is generally referred to as TEMPO-oxidized cellulose nanofibers and can also be used in this embodiment. The fine fibrous oxidized cellulose may have an aldehyde group or a ketone group together with the carboxyl group, but it is preferable that the fine fibrous oxidized cellulose does not substantially have the aldehyde group and the ketone group.

The content of the anionic functional group in the fine fibrous cellulose is not particularly limited, and may be, for example, 1.2 to 2.2 mmol / g or 1.2 to 2.0 mmol / g per dry mass of the fine fibrous cellulose. However, it may be 1.6 to 2.0 mmol / g. For the content of anionic functional group, for example, in the case of a carboxyl group, 60 mL of a 0.5 to 1% by mass slurry is prepared from a cellulose sample whose dry mass has been precisely weighed, and the pH is adjusted to about 2. with a 0.1 M aqueous hydrochloric acid solution. After setting to 5, a 0.05 M aqueous solution of sodium hydroxide was added dropwise, the electric conductivity was measured, and the pH was continued until the pH reached about 11, and the change in the electric conductivity was gradually consumed in the neutralization step of the weak acid. It can be obtained from the amount of sodium hydroxide (V) according to the following formula. The phosphoric acid group can also be measured by the same electric conductivity measurement. Other anion groups may also be measured by a known method.
Amount of anionic functional group (mmol / g) = V (mL) x [0.05 / cellulose sample mass (g)]

Fine fibrous cellulose is obtained by performing a defibration treatment. The defibration treatment may be carried out after the anionic functional group is introduced, or may be carried out before the introduction. As the defibration treatment, for example, a homomixer under high-speed rotation, a high-pressure homogenizer, an ultrasonic disperser, a beater, a disc-type refiner, a conical-type refiner, a double-disc-type refiner, a grinder, or the like is used to water the cellulose fibers. This can be done by treating the dispersion, and an aqueous dispersion of fine fibrous cellulose can be obtained.

The content of the fine fibrous cellulose (B) is preferably 0.05 to 0.5 parts by mass, more preferably 0.1 to 0.4 parts by mass with respect to 100 parts by mass of the inorganic material (A). It is a mass part.

[Water (C)]
Water (C) is added to make the inorganic material (A) into a clay-like state (that is, a plastic raw material) that can be extruded. The content of water (C) in the extrusion molding composition is not particularly limited, but is preferably 5 to 50 parts by mass, more preferably 10 to 30 parts by mass with respect to 100 parts by mass of the inorganic material (A). It is a mass part.

[Binder component (D)]
The binder component (D) is not particularly limited, and various water-soluble polymers that act as a binder for the inorganic material (A) can be used. Specific examples thereof include alkyl cellulose (for example, methyl cellulose, ethyl cellulose, propyl cellulose and the like), hydroxypropyl methyl cellulose, hydroxyethyl methoxy cellulose, water-soluble cellulose such as carboxymethyl cellulose, wheat flour and the like. Further, a commercially available binder for molding ceramics can be used. Specific examples thereof include YB-3N, YB-131D, YB-167, YB-152A, and YB-132A manufactured by Yuken Kogyo Co., Ltd.

The content of the binder component (D) is not particularly limited, and may be 1 to 30 parts by mass with respect to 100 parts by mass of the inorganic material (A), preferably 2 to 20 parts by mass from the viewpoint of fluidity and shape retention. It is a mass part.

[Extrusion molding composition]
In addition to the above components (A) to (D), the composition for extrusion molding according to the present embodiment includes, for example, a plasticizer, a sintering aid, an organic solvent, and an increase within a range that does not impair the effects of the present embodiment. Additives such as thickeners, lubricants, inorganic salts and plastic natural raw materials such as clay may be further added.

The composition for extrusion molding according to the present embodiment can be obtained by kneading the above components (A) to (D) using a kneader. The hardness of the obtained extrusion molding composition is not particularly limited, but is preferably 10 or more, more preferably 10 to 14, and even more preferably 11 to 13. When the hardness is 10 or more, appropriate operability in an extruder can be obtained, and it can be molded into a desired shape. In addition, the extrusion-molded composition for extrusion molding can be kept in shape and can maintain a molded state.

Here, the hardness of the composition for extrusion molding is measured by an NGK type hardness tester. That is, the tip of the probe of the NGK type hardness tester is vertically pressed against the obtained composition for extrusion molding, and the obtained value is taken as the hardness.

[Manufacturing method of extruded body]
In the method for producing an extruded product according to the present embodiment, the above-mentioned inorganic material (A), fine fibrous cellulose (B), water (C) and binder component (D), and if necessary, any additive are used. After kneading with a kneader to prepare an extrusion-molding composition, the obtained extrusion-molding composition is extruded by an extruder to produce an extrusion-molded body.

The composition for extrusion molding after kneading may be degassed according to a conventional method and then put into an extruder for extrusion molding. After extrusion molding, it may be dried to evaporate water. The obtained extruded body is cut into a predetermined size and then fired according to a conventional method to obtain a ceramic product.

[effect]
With the composition for extrusion molding according to the present embodiment, an increase in molding pressure is suppressed when passing through the base during extrusion molding, and the strength of the molded body after passing through the base can be increased, so that the fluidity is high. It is possible to achieve both the contradictory performance of shape retention and shape retention. Therefore, it is possible to provide molded bodies having various shapes such as honeycomb structures, pipes or rod-shaped structures while being excellent in mass productivity. For example, exhaust gas removal filters for automobiles, insulators, graphite electrodes, tiles, translucency. It can be used for molding various ceramic products such as alumina pipes, insulating substrates, electric or magnetic ceramics, and functional fibers.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

The extrusion molding compositions (soil) of Examples 1 to 8 and Comparative Examples 1 to 5 were prepared according to the formulations shown in Table 1 below. Specifically, the inorganic material, the aqueous dispersion of cellulose, water, and the binder component were weighed according to the formulation shown in Table 1, and stirred and mixed at room temperature for 1 minute with a high-speed mixer (manufactured by Miyazaki Iron Works Co., Ltd.). The obtained mixture was kneaded by passing an appropriate amount through the upper kneading portion of the kneading vacuum extrusion molding machine FM-P30 manufactured by Miyazaki Iron Works Co., Ltd. to obtain an extrusion molding composition.

The details of each component in Table 1 are as follows.
-Inorganic material (A1): Alumina, "AES-11" manufactured by Sumitomo Chemical Co., Ltd.
-Inorganic material (A2): Partially stabilized zirconia, "HSY-3.0" manufactured by Daiichi Rare Element Industry Co., Ltd.
-Cellulose aqueous dispersion (B1): 2% by mass dispersion of TEMPO oxidized fine fibrous cellulose-Cellulose aqueous dispersion (B2): 2% by mass dispersion of TEMPO oxidized fine fibrous cellulose-Cellulose aqueous dispersion (B3) : 2% by mass dispersion of TEMPO oxidized fine fibrous cellulose / water cellulose dispersion (B4): 2% by mass dispersion of TEMPO oxidized unfibrillated cellulose fiber / water cellulose dispersion (B5): of non-crystalline cellulose 2% by mass water dispersion / cellulose water dispersion (B6): Unmodified cellulose, "Selish KY100G" manufactured by Daisel Finecell Co., Ltd. (Unmodified fine fibrous cellulose obtained by mechanically pulverizing cellulose fibers, 10 Mass% aqueous dispersion, number average fiber diameter = 100 nm, average aspect ratio = 5000) diluted to 2% by mass with water ・ Cellulose-based binder: Methyl cellulose, "Metro's" manufactured by Shin-Etsu Chemical Industry Co., Ltd.
-Organic binder: Commercially available ceramic molding binder, "YB-131D" manufactured by Yuken Kogyo Co., Ltd.

The aqueous cellulose dispersions (B1) to (B4) were prepared by the following methods.

[Manufacturing of water-based cellulose dispersion (B1)]
First, 150 ml of water, 0.25 g of sodium bromide, and 0.025 g of TEMPO were added to 2 g of coniferous pulp, and after sufficiently stirring and dispersing, a 13 mass% sodium hypochlorite aqueous solution (cooxidant) was added. Sodium hypochlorite was added to 1.0 g of the above pulp so that the amount of sodium hypochlorite was 12.0 mmol / g, and the reaction was started. Since the pH decreases as the reaction progresses, a 0.5 N aqueous sodium hydroxide solution was added dropwise to maintain the pH at 10 to 11, and the reaction was carried out until no change in pH was observed (reaction time: 120 minutes). ). After completion of the reaction, 0.1N hydrochloric acid was added for neutralization, and then filtration and washing with water were repeated for purification to obtain cellulose fibers having an oxidized fiber surface. Subsequently, after solid-liquid separation with a centrifuge, purified water was added to adjust the solid content concentration to 4% by mass. Then, the pH of the slurry was adjusted to 10 with a 24% NaOH aqueous solution. The temperature of the slurry was set to 30 ° C., 0.3 g (0.2 mmol / g) of NaBH ₄ was added, and the mixture was reacted for 2 hours for reduction treatment. After the reaction, 1M HCl was added to neutralize the mixture, and the mixture was purified by repeating filtration and washing with water to obtain cellulose fibers. Next, pure water and sodium hydroxide were added in appropriate amounts to the cellulose fibers to dilute them to 2% by mass, and treated once with a high-pressure homogenizer (H11, manufactured by Sanwa Engineering Co., Ltd.) at a pressure of 100 MPa to obtain a cellulose aqueous dispersion. (B1) was obtained. As measured by the method described later, the obtained cellulose aqueous dispersion (B1) contained 1.98 mmol / g of the carboxyl group of the anion-modified fine fibrous cellulose and 0.10 mmol of the carbonyl group. / G, on the other hand, no detection of aldehyde groups was observed. The number average fiber diameter of the anion-modified fine fibrous cellulose contained in the aqueous cellulose dispersion (B1) was 4 nm, and the average aspect ratio was 280. When the crystal structure of the cellulose contained in the modified fine fibrous cellulose was confirmed by wide-angle X-ray diffraction image measurement, the type I crystal structure was "yes". In addition, the peak of 62 ppm corresponding to the C6 position of the primary hydroxyl group of the glucose unit, which can be confirmed on the ¹³ C-NMR chart of cellulose before oxidation, disappears after the oxidation reaction, and instead, the peak derived from the carboxyl group is 178 ppm. Was appearing. Therefore, it was confirmed that only the C6-position hydroxyl group of the glucose unit was oxidized to the carboxyl group or the like.

[Manufacturing of water-based cellulose dispersion (B2)]
The sodium hypochlorite aqueous solution to be added was oxidized by the same method as the aqueous cellulose dispersion (B1) except that the amount of sodium hypochlorite was 5.2 mmol / g with respect to 1.0 g of the above pulp. Reduced and purified. Next, pure water and sodium hydroxide were added in appropriate amounts to the cellulose fibers to dilute them to 2% by mass, and treated once with a high-pressure homogenizer (H11, manufactured by Sanwa Engineering Co., Ltd.) at a pressure of 100 MPa to obtain a cellulose aqueous dispersion. (B2) was obtained. As measured by the method described later, the obtained cellulose aqueous dispersion (B2) contained 1.97 mmol / g of the carboxyl group of the anion-modified fine fibrous cellulose and 0.10 mmol of the carbonyl group. / G, on the other hand, no detection of aldehyde groups was observed. The number average fiber diameter of the anion-modified fine fibrous cellulose contained in the aqueous cellulose dispersion (B2) was 89 nm, and the average aspect ratio was 92. When the crystal structure of the cellulose contained in the modified fine fibrous cellulose was confirmed by wide-angle X-ray diffraction image measurement, the type I crystal structure was "yes". In addition, the peak of 62 ppm corresponding to the C6 position of the primary hydroxyl group of glucose unit, which can be confirmed on the ¹³ C-NMR chart of cellulose before oxidation, disappears after the oxidation reaction, and instead, the peak derived from the carboxyl group is 178 ppm. Was appearing. Therefore, it was confirmed that only the C6-position hydroxyl group of the glucose unit was oxidized to the carboxyl group or the like.

[Manufacturing of water-based cellulose dispersion (B3)]
In the step of dispersing the cellulose fibers after the oxidation and reduction treatment, the cellulose aqueous dispersion (B3) is similar to the production of the cellulose aqueous dispersion (B1) except that an appropriate amount of triethanolamine is used instead of sodium hydroxide. Got

When measured by the method described later, the obtained cellulose aqueous dispersion (B3) contained 1.97 mmol / g of carboxyl group and 0.10 mmol of carbonyl group of anion-modified fine fibrous cellulose. / G, on the other hand, no detection of aldehyde groups was observed. The number average fiber diameter of the anion-modified fine fibrous cellulose contained in the aqueous cellulose dispersion (B3) was 6 nm, and the average aspect ratio was 245. When the crystal structure of the cellulose contained in the modified fine fibrous cellulose was confirmed by wide-angle X-ray diffraction image measurement, the type I crystal structure was "yes". In addition, the peak of 62 ppm corresponding to the C6 position of the primary hydroxyl group of glucose unit, which can be confirmed on the ¹³ C-NMR chart of cellulose before oxidation, disappears after the oxidation reaction, and instead, the peak derived from the carboxyl group is 178 ppm. Was appearing. Therefore, it was confirmed that only the C6-position hydroxyl group of the glucose unit was oxidized to the carboxyl group or the like.

[Manufacturing of water-based cellulose dispersion (B4)]
The sodium hypochlorite aqueous solution to be added is oxidized and reduced by the same method as the aqueous cellulose dispersion (B1) except that the amount of sodium hypochlorite is 4.1 mmol / g with respect to 1.0 g of the above pulp. Then, after neutralizing by adding 0.1N hydrochloric acid, it was purified by repeating filtration and washing with water to obtain a cellulose aqueous dispersion (B4) containing undissolved cellulose fibers whose fiber surface was oxidized. As a result of measurement by the method described later, the obtained cellulose aqueous dispersion (B4) contains 1.0 mmol / g of carboxyl group and 0 carbonyl group in the anion-modified undissolved cellulose fiber. It was .10 mmol / g, while no aldehyde group was detected. The number average fiber diameter of the anion-modified undissolved cellulose fibers contained in the aqueous cellulose dispersion (B4) was 182 nm, and the average aspect ratio was 77. When the crystal structure of the cellulose contained in the modified undeveloped cellulose fiber was confirmed by wide-angle X-ray diffraction image measurement, the type I crystal structure was "yes". In addition, the peak of 62 ppm corresponding to the C6 position of the primary hydroxyl group of the glucose unit, which can be confirmed on the ¹³ C-NMR chart of cellulose before oxidation, disappears after the oxidation reaction, and instead, it is derived from the carboxyl group at 178 ppm. A peak was appearing. Therefore, it was confirmed that only the C6-position hydroxyl group of the glucose unit was oxidized to the carboxyl group or the like.

[Manufacturing of water-based cellulose dispersion (B5)]
Cellulose water was used instead of coniferous pulp as a raw material, except that the sodium hypochlorite aqueous solution to be added was 27.0 mmol / g of sodium hypochlorite with respect to 1.0 g of regenerated cellulose. An aqueous cellulose dispersion (B5) was prepared in the same manner as the dispersion (B1). The obtained aqueous cellulose dispersion (B5) had an unmeasurable number average fiber diameter (1 nm or less), a carboxyl group amount of 3.1 mmol / g, and did not have a crystal structure.

Using the produced anion-modified fine fibrous cellulose as a sample, each characteristic was measured as follows.

[Measurement of carboxyl group amount]
60 ml of an aqueous dispersion in which 0.25 g of a sample is dispersed in water is prepared, the pH is adjusted to about 2.5 with a 0.1 M aqueous hydrochloric acid solution, and then a 0.05 M aqueous sodium hydroxide solution is added dropwise to conduct electrical conduction. The degree was measured. The measurement was continued until the pH reached about 11. From the amount of sodium hydroxide (V) consumed in the neutralization step of the weak acid with a gradual change in electrical conductivity, the amount of carboxyl group was determined according to the following formula (1).
Carboxyl group amount (mmol / g) = V (mL) × [0.05 / cellulose sample mass (g)]… (1)

[Measurement of carbonyl group amount (semicarbazide method)]
Approximately 0.2 g (dry mass) of the sample was precisely weighed, and exactly 50 ml of a 3 g / l aqueous solution of semicarbazide hydrochloride adjusted to pH = 5 with a phosphate buffer solution was added, the mixture was sealed, and the mixture was shaken for 2 days. Then, 10 ml of this solution was accurately collected in a 100 ml beaker, 25 ml of 5N sulfuric acid and 5 ml of a 0.05 N potassium iodate aqueous solution were added, and the mixture was stirred for 10 minutes. Then, 10 ml of a 5% potassium iodide aqueous solution was added, and the sample was immediately titrated with a 0.1 N sodium thiosulfate solution using an automatic titrator, and the titration amount was determined according to the following formula (2) in the sample. The amount of carbonyl group (total content of aldehyde group and ketone group) was determined.
Carbonyl group amount (mmol / g) = (DB) × f × [0.125 / w]… (2)
D: Sample titration (ml)
B: Titration of blank test (ml)
f: Factor of 0.1N sodium thiosulfate solution (-)
w: Sample amount (g)

[Detection of aldehyde group]
After weighing 0.4 g of the sample and adding a failing reagent (5 ml of a mixed solution of sodium potassium tartrate and sodium hydroxide and 5 ml of an aqueous solution of copper sulfate pentahydrate) prepared according to the Japanese Pharmacopoeia, 1 at 80 ° C. Heated for hours. When the supernatant was blue and the sample portion (solid content) was dark blue, it was judged that no aldehyde group was detected, and the sample was evaluated as "none". In addition, when the supernatant was yellow and the sample part was red, it was judged that an aldehyde group was detected, and it was evaluated as "yes".

[Number average fiber diameter]
The number average fiber diameter of the anion-modified fine fibrous cellulose was observed using a transmission electron microscope (TEM) (JEM-1400, manufactured by JEOL Ltd.). That is, after casting the sample on the hydrophilized carbon film-coated grid, the number average fiber diameter was determined from the TEM image (magnification: 10,000 times) negatively stained with a 2% uranyl acetate aqueous solution according to the method described above. Calculated.

[Average aspect ratio]
The average aspect ratio of the anion-modified fine fibrous cellulose was measured as follows. That is, the sample was cast on a hydrophilicized carbon film-coated grid, and then negatively stained with a 2 mass% uranyl acetate aqueous solution from a TEM image (magnification: 10,000 times), and anion-modified according to the method described above. Observe the number average width of the shorter width (short width) and the number average width of the longer width (long width) of the fine fibrous cellulose, and from these values, the average aspect according to the method described above. The ratio was calculated.

[Crystal structure]
The diffraction profile of the sample is measured using an X-ray diffractometer (RINT-Ultima3, manufactured by Rigaku), which is typical of two positions, 2 theta = 14 to 17 ° and 2 theta = 22 to 23 °. When no peak was observed, the crystal structure (type I crystal structure) was evaluated as "present", and when no peak was observed, it was evaluated as "absent".

[Selective oxidation for C6 position]
It was confirmed by the ¹³ C-NMR chart whether or not only the hydroxyl group at the C6 position of the glucose unit on the sample surface was selectively oxidized to the carboxyl group or the like.

The hardness of each of the obtained extrusion molding compositions was measured. Further, extrusion molding was performed using each extrusion molding composition, the molding pressure at that time was measured, and the three-point bending strength after drying the obtained molded product was measured.

These measurement methods are as follows.
-Hardness: Measured with an NGK type hardness tester manufactured by NGK Insulators, Ltd. For each of the obtained extrusion-molded compositions, the tip of the probe of the NGK type hardness tester was pressed vertically, three measurement points were scored, and the average value of the measured values was taken as the hardness.
Molding pressure: Using Autograph AGS-10K manufactured by Shimadzu Corporation as an extruder, a sheet-shaped molded product with a thickness of 4.0 mm was extruded from a cylinder with a diameter of 30 mm by low-speed molding with a head speed of about 40 mm / min. The total load at the time was measured.
-Three-point bending strength: After drying the molded product having a thickness of 4.0 mm obtained by the above extrusion molding in a batch dryer at 105 ° C. for 60 minutes, a universal testing machine (Autograph AG-500D, according to JIS R1601). Shimadzu Corporation) measured the three-point bending strength.

The results are shown in Table 1. In Examples 1 to 8 in which anionic-modified fine fibrous cellulose (TEMPO-oxidized cellulose nanofibers) was added, in contrast to Comparative Example 1 in which the control was not added with cellulose fibers, a significant increase in molding pressure was suppressed. However, it was possible to improve the hardness and the three-point bending strength.

Further, when Comparative Example 2 to which the machine-ground unmodified cellulose was added and Example 3 to which the same amount of anion-modified cellulose fibers were added, the three-point bending strength was compared with Comparative Example 2 to which the unmodified cellulose was added. The improvement effect of Example 3 in which the anion-modified fine fibrous cellulose was added was greater than that in Example 3. On the other hand, the molding pressure was significantly higher in Comparative Example 2 in which the unmodified cellulose was added than in Example 3 in which the anion-modified fine fibrous cellulose was added. The higher the molding pressure, the lower the fluidity. Therefore, from the above results, it was obtained that the anion-modified fine fibrous cellulose has a higher effect of increasing the strength of the molded body than the unmodified cellulose and the amount of increase in viscosity is low. .. Therefore, it can be said that the anion-modified fine fibrous cellulose is an organic additive suitable for forming thin materials such as honeycombs.

In Comparative Example 3, undefibrated TEMPO-oxidized cellulose fiber was added, and the undefibrated material was unevenly present in the clay, so that it could not be molded. Further, in Comparative Example 4, non-crystalline cellulose was added, and the effect of improving the hardness and the three-point bending strength could not be obtained. In Comparative Example 5, since the binder component was not blended, the clay was brittle and could not be molded.

Although some embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments, omissions, replacements, changes, etc. thereof are included in the scope and gist of the invention, as well as in the scope of the invention described in the claims and the equivalent scope thereof.

Claims (7)

It contains an inorganic material (A), fine fibrous cellulose (B), water (C), and a binder component (D), and the fine fibrous cellulose (B) has the following conditions (a) and (b). , (C) and (d), an extrusion-molding composition.
(A) Number average fiber diameter is 3 nm or more and 100 nm or less (b) Average aspect ratio is 50 or more and 1000 or less (c) Cellulose type I crystal structure (d) Anionic functional group It contains an inorganic material (A), fine fibrous cellulose (B), water (C), and a binder component (D), and the fine fibrous cellulose (B) has the following conditions (a) and (b). , (C) and (d) are satisfied, and the content of the fine fibrous cellulose (B) is 0.05 to 0.5 parts by mass with respect to 100 parts by mass of the inorganic material (A). Composition for extrusion molding.
(A) Number average fiber diameter is 3 nm or more and 100 nm or less
(B) Average aspect ratio is 10 or more and 1000 or less
(C) Has a cellulose type I crystal structure
(D) Has an anionic functional group It contains an inorganic material (A), fine fibrous cellulose (B), water (C), and a binder component (D), and the fine fibrous cellulose (B) has the following conditions (a) and (b). , (C) and (d), and a composition for extrusion molding having a hardness of 10 or more.
(A) Number average fiber diameter is 3 nm or more and 100 nm or less
(B) Average aspect ratio is 10 or more and 1000 or less
(C) Has a cellulose type I crystal structure
(D) Has an anionic functional group The composition for extrusion molding according to any one of claims 1 to 3, wherein the anionic functional group of the fine fibrous cellulose (B) is a carboxyl group. The item according to any one of claims 1 to 4, wherein the content of the anionic functional group of the fine fibrous cellulose (B) is 1.2 to 2.2 mmol / g per dry mass of the fine fibrous cellulose. The composition for extrusion according to description. The composition for extrusion molding according to any one of claims 1 to 5, wherein the content of the binder component (D) is 2 to 20 parts by mass with respect to 100 parts by mass of the inorganic material (A). thing. A method for producing an extruded body, wherein the extruded composition according to any one of claims 1 to 6 is extruded to produce an extruded body.